Apparatus for calibrating timing devices



April 3, 1934. D A Y UN 1,953,148

APPARATUS FOR CALIBRATING TIMING DEVICES Filed Oct. 6, 1930 Tmmg lEu-K.

.BALB,

INVENTOR Doug/ass /7 6un9.

anpllymand Patented Apr. 3, 1934 PATENT OFFICE APPARATUS FOR CALIBRATING 'mnno navrcas Douglass A. Young, East Orange, N. 1., assignor to Westinghouse Electric 8; Manufacturing Company, a corporation of Pennsylvania Application October 8,

1930, Serial No. 486,697

- 1 Claim. (cits- 51) My invention relates to apparatus for calibrating precision instruments and hasspecial relation to calibrating timing instruments, such as clocks and watches. An object of myinvention is to provide app ratus of the above mentioned character by means of which the moving parts of a watch or clock are stroboscopically compared with an object moving at a standard rate of speed.

Another object of my invention is to provide apparatus, as described above, in which a relatively small error in the timing of a watch may be amplifled and observed on avisible indicating device.

The former practice in calibrating watches has very short space of time, usually not morethan one minute.

For a better understanding of. my invention, reference may be had to the following description, taken in conjunction with the accompanying drawing, in which The single figure is a schematic view of a callbrating mechanism,. constructed in accordance 1 with my invention.

Referring to the drawing, a watch mechanism 1, comprising a casing 2 and an adjusting dial 3,

is shown. The dial face 3 is provided with the usual calibrating scale 4. A calibrating lever 5 cooperates with the scale 4 in the usualmannen A balance wheel 6 protrudes from the casing 2.

An opening 7 is drilled in the periphery of the balance wheel 6, for a purpose to be hereinafter more fully explained.

An incandescent lamp 8 is connected, through conductors 9 and 10, to a source of power (not 4 shown). The lamp 8 is enclosed in a casing 11. A condensing lens 12 is provided at one end of the casing 11. i A mirror 13 is'placed adjacent to the watch mechanism. A photo-electric cell 14 is connected,

' through conductors 15 and 16, to an amplifying unit 1'7. A neon lamp 18 is energized, through conductors 19 and 20, from the amplifying unit 17. 'A viewing disc 21 is fixedly secured to a shaft 22. A pinion 23 is connected or otherwise secured to the shaft 22. The pinion 23 is adaptedto mesh with the gear member 24, which is'keyed to a shaft 25 of a synchronous motor 26. The synchronous motor 26 is connected, through conductors 27 and 28, to a standard-frequency device'29 comprising I V a tuning fork and an amplifier. The frequency device 29 is connected. through conductors 30 and 31, to a source of energy (not shown).

The viewing disc 211:; provided with a circular aperture 32 near its peripheral edge for a purpose to be hereinafter more fully explained. 55

The operation of the device is as follows:

The lamp 8 is lighted,'and the timing device is placed at a point where the light beam from the lamp 8 is concentrated, by means of the lens 12, to a spot on the periphery of the balance wheel 6. The watch mechanism 1 is then started. As the balance wheel 6 oscillates, the aperture 7 allows a beam'of light from the lamp 8 to intermittently impinge upon the mirror 13. The mirror 13 reflects the'intermittent flashes of light upon the photo-electric cell 14. The electrical impulses set up within the photo-electric cell 14 are amplified by the amplifying unit .17 and serve to intermittently light the neon lamp 18. .The synchronous motor 26 is run at a frequency determined by the standard-frequency device 29. The frequency device 29 is of a type in which the frequency is determined by a tuning fork and an amplifying device. The frequency at which the synchronous motor 26 is run is thus essentially a 85 standard of time. The viewing disc 21 is geared to the synchronous motor 26 in such manner that the speed of the viewing disc is proportional to and a multiple of, the speed of the synchronous motor.

The neon lamp 18 is thus lighted in accordance with the speed of oscillation of the balance wheel 6 of the watch mechanism, and if the watch is perfectly timed, the aperture 32 of the viewing disc will appear to stand still, because of the well known stroboscopic effect. If, however, the timing of the balance wheel 6 is slow, the aperture 32 of the viewing disc 21'will appear to rotate in onedirection. In the same manner, if the timing of the balance wheel 6- is fast, 1 the aperture 32 of the viewing disc 21 will appear to rotate in the opposite direction. To correct the timing of the watch mechanism, the lever B is moved in the one or the other direction, along the scale 4'. When-the aperture-32 of the view- 1 ing disc appears to be stationary, the operator or observer will know that the oscillation of the balance wheel 6 is in synchronism with the frequency of the motor 26, which is governed by f the standard of time, and that the watch in call-- 110 brated. Since the viewing disc 21 is rotated at a multiple of the speed of the synchronous motor 26, a. relatively small error in the speed of oscillation of the balance wheel 6 will cause a large phase displacement between the aperture 32 and viewing consecutive flashes of the neon lamp. This feature will allow a much closer calibration of the watch mechanism.

If desired, instead of perforating the rim of the balance wheel 6, a piece of reflecting material may be placed on the balance wheel to periodically reflect a beam of light from the lamp 8 directly to the photo-electric cell 14, or the wheel may reflect, and a small dark spot may intercept the light.

I do not wish to be restricted to the specific arrangements of parts and structural details herein set forth, as it is evident that various modifications thereof will fall within the spirit and scope of my invention. I desire, therefore, that only such limitations be imposed as are indicated in the appended claim.

ance with the impulses generated by said cell,

a standard-time device comprising a source of constant frequency electromotive force and a rotatable device driven thereby at a speed which is a multiple of the periodicity of said balance wheel when it isaccurately regulated; said standard-time device and gas-filled lamp being so disposed that the speed of rotation of the former and the frequency of illumination of the latter may be stroboscopically compared.

DOUGLASS A. YOUNG. 

